Petal Blight Botrytis cinerea is a fungus that spots orchid flowers. To infect, it requires water on the flower surface, so it is a problem when humidity levels are so high as to lead to water condensation on the flowers. Water persisting on flowers after a rain or watering will encourage Botrytis. Symptoms : Black [...]

Bacterial Brown Spot This disease is most prevalent in phalaenopsis, and is as deadly as black rot is with cattleyas. It is especially active under wet and coot conditions. Symptoms : Infection by Pseudomonas cattleyas, the bacterium involved, starts as a brown, watery blister on a leaf and quickly spreads, engulfing whole leaves. If it [...]

Viruses Several viruses are known for orchids in cultivation. Three viruses are prevalent among orchids: cymbidium mosaic virus (CyMV), tobacco mosaic virus (TMV) and bean yellow mosaic. Symptoms are non-specific and can easily be confused with symptoms of bacterial and fungal diseases or even cultural problems. But plants with yellow to black streaks on the [...]

Scale Quite a few species of scale infest orchids. Scale insects secrete a hard, waxy covering that repels most pesticides unless a wetting agent is added. Their presence is often first noticed by the sticky “honeydew” that they secrete. Large infestations can be very difficult to eradicate even with highly toxic pesticides. Symptoms : Scale [...]